1. Field of the Invention
The invention relates to an injector for hypodermically implanting an object in a living being, comprising a housing accommodating a needle (holder) in such a way that it is slidable out of said housing, on which needle(holder) a spring acts, said spring being tensioned during the outward movement of the needle, with a push rod fitted in said hollow needle for conveyance of the object, with unlocking means fitted on the housing near the outlet aperture of the needle, for detecting contact with the living being and starting the positioning of the object in the living being, and with control means for moving the needle out of the housing.
2. Description of the Invention
Such an injector is known from Dutch Patent Application 8,902,283. The spring force necessary for the various actions is produced in it by means of a tensioning handle. The needle in this case is situated in the housing when in the storage position. For the implantation of an object, the injector is moved against the animal with the needle fitted in the housing. The unlocking means are thereby operated. Said unlocking means release the control means. These control means are a puller. By means of said puller, a spring-loaded slide is released, so that the needle shoots into the animal. This means that the user does not see the insertion movement of the needle into the animal, because the injector is always held against the animal. Disconnection of the needle and the slide takes place at the end of the movement of the needle into the animal. This means that the needle is moved back out of the animal, with the slide remaining in the same position. A push rod which does not make such a return movement is also connected to the slide. Due to the fact that during the implantation an object to be implanted, such as a transponder, is placed in front of the push rod, when the needle is withdrawn and the push rod remains in place, such a transponder will be placed in the animal.
A number of disadvantages are associated with the use of this device. For tensioning of the injector, energy must be supplied both for the withdrawal of the needle and for the insertion of the needle. For, only a blocking is released by the control means. The energy required in particular during insertion of the needle is very variable. One skin is easier to pierce than another skin, due to greater thickness or other circumstances, while the state of the tissue under the skin can vary widely. This means that, either a very great pre-tensioning force is needed, which on relatively easy penetration causes too great a shock and could damage the object to be implanted, or not enough force is used to ensure that the needle penetrates sufficiently into the animal in all circumstances. If there is inadequate penetration into the animal, the placing of the transponder can go completely wrong.
Another disadvantage of this device is that, if it is in the tensioned state, the needle is present under spring tension in the housing. It is extremely simple for unskilled people, and in particular children, to injure themselves by pressing the unlocking means when engaging the control means.